Abstract:

A determination image generator of an image processing apparatus compares,
in pixel units, sixth image data with seventh image data or second image
data. The sixth image data is obtained by selecting, in pixel units, a
minimum value of a value of first image data and a value of fifth image
data which is edge enhanced data of the first image data. The seventh
image data is obtained by performing first processing to second image
data. The generator sets in the determination image a third value for
pixels where a value of the sixth image data is equal to or less than a
value of the seventh image data or the second image data, or is equal to
or less than a sum of the value of the seventh image data or the second
image data and a first value, and sets a different value for all other
pixels.

Claims:

1. An image processing apparatus comprising a generator that compares, in
pixel units, sixth image data with seventh image data or second image
data, and generates a determination image,wherein the sixth image data is
obtained by selecting, in pixel units, a minimum value of a value of
first image data of a determination target and a value of fifth image
data obtained by performing edge enhancement processing to the first
image data,the seventh image data is obtained by performing preset first
processing with respect to second image data for comparison representing
the same image as the first image data, andthe generator sets in the
determination image a preset third value for pixels where a value of the
sixth image data is equal to or less than a value of the seventh image
data or the second image data, or is equal to or less than a sum of the
value of the seventh image data or the second image data and a preset
first value, and sets a value different from the third value for all
other pixels.

2. The image processing apparatus according to claim 1, wherein the first
processing obtains the seventh image data by selecting, in pixel units, a
maximum value of a value of third image data obtained by performing
smoothing processing to the second image data, a value of fourth image
data obtained by performing edge enhancement processing to the second
image data, and a value of eighth image data obtained by respectively
selecting a maximum value of values of neighboring plural pixels for
individual pixels of the second image data as values of those pixels,
andthe generator compares, in pixel units, the sixth image data with the
seventh image data.

3. The image processing apparatus according to claim 1, wherein the
generator further sets, in the determination image, the third value for
pixels where a value of third image data obtained by performing smoothing
processing to the second image data is equal to or greater than a sum of
the value of the second image data and a preset sixth value and where a
value of fourth image data obtained by performing edge enhancement
processing to the second image data is smaller than a preset seventh
value.

4. An image processing apparatus comprising a generator that compares, in
pixel units, sixth image data or first image data with seventh image data
and generates a determination image,wherein the sixth image data is
obtained by performing preset second processing with respect to first
image data of a determination target,the seventh image data is obtained
by selecting, in pixel units, a maximum value of a value of third image
data, a value of fourth image data and a value of eighth image data,the
third image data is obtained by performing smoothing processing to second
image data for comparison representing the same image as the first image
data,the fourth image data is obtained by performing edge enhancement
processing to the second image data,the eighth image data is obtained by
respectively selecting a maximum value of values of neighboring plural
pixels for individual pixels of the second image data as values of those
pixels, andthe generator sets, in the determination image, a preset third
value for pixels where a value of the sixth image data or the first image
data is equal to or less than a value of the seventh image data, or is
equal to or less than a sum of the value of the seventh image data and a
preset first value, and sets a value different from the third value for
all other pixels.

5. An image processing apparatus comprising a generator that compares, in
pixel units, tenth image data with seventh image data or second image
data, and generates a determination image,wherein the tenth image data is
obtained by selecting, in pixel units, a minimum value of a value of
first image data of a determination target and a value of ninth image
data,the ninth image data is obtained by respectively selecting a minimum
value of values of neighboring plural pixels for individual pixels of
fifth image data obtained by performing edge enhancement processing with
respect to the first image data as values of those pixels,the seventh
image data are is by performing preset first processing with respect to
second image data for comparison representing the same image as the first
image data, andthe generator sets, in the determination image, a preset
third value for pixels where the value of the tenth image data is equal
to or less than a value of the seventh image data or the second image
data, or is equal to or less than a sum of the value of the seventh image
data or the second image data and a preset first value, and sets a value
different from the third value for all other pixels.

6. An image processing apparatus comprising a generator that compares, in
pixel units, sixth image data or first image data with seventh image data
or second image data, and generates a determination image,wherein the
sixth image data is obtained by performing preset second processing with
respect to first image data of a determination target,the seventh image
data is obtained by performing preset first processing with respect to
second image data for comparison representing the same image as the first
image data, andthe generator sets, in the determination image, a preset
third value for first pixels where a value of the sixth image data or the
first image data is equal to or less than a value of the seventh image
data or the second image data, or is equal to or less than a sum of a
value of the seventh image data or the second image data and a preset
first value, and for second pixels where a value of third image data
obtained by performing smoothing processing to the second image data is
equal to or greater than a sum of the value of the second image data and
a preset sixth value and where a value of fourth image data obtained by
performing edge enhancement processing to the second image data is
smaller than a preset seventh value, and sets a value different from the
third value for all other third pixels.

7. The image processing apparatus according to claim 5, wherein the first
processing obtains the seventh image data by selecting, in pixel units, a
maximum value of the second image data, a value of third image data
obtained by performing smoothing processing to the second image data, and
a value of fourth image data obtained by performing edge enhancement
processing to the second image data, andthe generator compares, in pixel
units, the sixth image data or the tenth image data with the seventh
image data.

8. An image processing apparatus comprising a generator that compares, in
pixel units, a value of first image data of a determination target with a
value of eleventh image data, and generates a determination image,wherein
the eleventh image data is obtained by performing, with respect to second
image data for comparison representing the same image as the first image
data, smoothing processing that causes a change in value in an edge
portion in an image to approximate the change in the first image data,
andthe generator sets, in the determination image, a preset third value
for pixels where the value of the first image data is equal to or less
than the value of the eleventh image data, or is equal to or less than a
sum of the value of the eleventh image data and a preset first value, and
sets a value different from the third value for all other pixels.

9. The image processing apparatus according to claim 1, wherein the
generator further sets the third value for pixels where the value of the
second image data is equal to or less than a preset second value.

10. The image processing apparatus according to claim 1, wherein the value
different from the third value is a value corresponding to a difference
between the value of the sixth image data or the tenth image data or the
first image data, and the value of the seventh image data or the second
image data or the third image data or the eleventh image data.

11. An image processing apparatus comprising a generator that compares, in
pixel units, determination target first image data and second image data
for comparison representing the same image as the first image data, and
generates a determination image, the generator sets, in the determination
image, a preset third value for pixels where the value of the first image
data is equal to or less than the value of the second image data, or is
equal to or less than the sum of the value of the second image data and a
preset first value, and for pixels where the value of the second image
data is equal to or less than a preset second value, and sets a value
that is different from the third value for all other pixels.

12. The image processing apparatus according to claim 11, wherein the
third value is a value corresponding to the difference between the value
of the first image data and the value of the second image data.

13. The image processing apparatus according to claim 11, wherein the
generator compares, in pixel units, the first image data respectively
with the second image data, third image data obtained by performing
smoothing processing to the second image data, and fourth image data
obtained by performing edge enhancement processing to the second image
data, and sets, in the determination image, the third value for pixels
where the value of the first image data is equal to or less than a
maximum value of the value of the second image data, the value of the
third image data and the value of the fourth image data, or is equal to
or less than the sum of the maximum value and the first value, and for
pixels where the value of the second image data is equal to or less than
the second value, and sets a value that is different from the third value
for all other pixels.

14. The image processing apparatus according to claim 13, wherein the
value that is different from the third value is a value corresponding to
the difference between the value of the first image data and the value of
the third image data.

15. The image processing apparatus according to claim 1, wherein the
generator generates the determination-use image per each color of image
data when the first image data and the second image data comprise two or
more colors.

16. The image processing apparatus according to claim 1, wherein the
generator comprises a pixel number adjuster that, when at least one of
the resolution and the number of pixels of the second image data is
different from that of the first image data, performs at least one of
resolution conversion and pixel addition with respect to at least one of
the first image data and the second image data and causes the resolution
and the number of pixels of plurality of sets of the image data to match
that of the first image data.

17. The image processing apparatus according to claim 1, wherein the
generator comprises a first smoothing processor that performs smoothing
processing with respect to the first image data, and the generator uses
the first image data to which the smoothing processing has been performed
for the comparison of image data in pixel units and the generation of the
determination image.

18. The image processing apparatus according to claim 17, wherein the
first image data are multi-value image data that have been obtained by
converting binary image data representing, gradations per unit region
that comprise the plural pixels with plural pixels that each take two
values, the multi-value image data representing gradations per individual
pixel with the individual pixels that each take multiple values, andthe
first smoothing processor performs the smoothing processing with respect
to the first image data using, as a unit, a local region that is equal to
or greater than the size of the unit region of the first image data and
is smaller than the period of moire on the first image data which is the
determination target.

19. The image processing apparatus according to claim 18, wherein the
generator comprises a second smoothing processor that performs smoothing
processing with respect to the second image data using, as a unit, a
local region that is smaller than the local region in the smoothing
processing with respect to the first image data, and the generator uses
the second image data to which the smoothing processing has been
performed for the comparison of image data in pixel units and the
generation of the determination image.

20. The image processing apparatus according to claim 1, further
comprising:an enhancement processor that performs enhancement processing
that increases the difference of the value of individual pixels with
respect to the generated determination image andan image output unit that
outputs the determination image to which the enhancement processing has
been performed.

21. The image processing apparatus according to claim 20, wherein the
generator generates the determination image per each color of image data
when the first image data and the second image data comprise two or more
colors,the enhancement processor performs the enhancement processing with
respect to the determination images per each color that have been
generated by the generator, andthe image output unit generates and
outputs a single image in which the determination images per each color
to which the enhancement processing has been performed have been reduced
and arrayed.

22. The image processing apparatus according to claim 1, whereinthe
generator generates a determination image in which the third value is set
to 0, and the value that is different from the third value is set to a
value corresponding to the difference between the value of the sixth
image data or the first image data, and the value of the seventh image
data or the second image data, andthe image processing apparatus further
comprisesa counter that counts the number of pixels in the generated
determination image that are equal to or greater than a preset fourth
value anda determination output unit that determines whether or not the
counting result is equal to or greater than a preset fifth value and
outputs the counting result.

23. An image processing system comprising:the image processing apparatus
according to claim 1;and at least one of a plate making device that
creates a printing plate that is used in a printing performed by a
printing device using the first image data, or an image formation device
that performs image formation using the second image data.

24. An image processing system comprising:the image processing apparatus
according to claim 4;and at least one of a plate making apparatus that
creates a printing plate that is used in a printing performed by a
printing device using the first image data, or an image formation
apparatus that performs image formation using the second image data.

25. An image processing system comprising:the image processing apparatus
according to claim 5;and at least one of a plate making apparatus that
creates a printing plate that is used in a printing performed by a
printing device using the first image data, or an image formation
apparatus that performs image formation using the second image data.

26. An image processing system comprising:the image processing apparatus
according to claim 6;and at least one of a plate making apparatus that
creates a printing plate that is used in a printing performed by a
printing device using the first image data, or an image formation
apparatus that performs image formation using the second image data.

27. An image processing system comprising:the image processing apparatus
according to claim 11;and at least one of a plate making apparatus that
creates a printing plate that is used in a printing performed by a
printing device using the first image data, or an image formation
apparatus that performs image formation using the second image data.

28. A storage medium storing a program to cause a computer to perform an
image processing, the image processing comprising:comparing, in pixel
units, sixth image data with seventh image data or second image
data;generating a determination image, wherein the sixth image data is
obtained by selecting, in pixel units, a minimum value of a value of
first image data of a determination target and a value of fifth image
data obtained by performing edge enhancement processing to the first
image data, the seventh image data is obtained by performing preset first
processing with respect to second image data for comparison representing
the same image as the first image data; andsetting in the determination
image a preset third value for pixels where a value of the sixth image
data is equal to or less than a value of the seventh image data or the
second image data, or is equal to or less than a sum of the value of the
seventh image data or the second image data and a preset first value, and
sets a value different from the third value for all other pixels.

29. A storage medium storing a program to cause a computer to perform an
image processing, the image processing comprising:comparing, in pixel
units, sixth image data or first image data with seventh image
data;generating a determination image, wherein the sixth image data is
obtained by performing preset second processing with respect to first
image data of a determination target, the seventh image data is obtained
by selecting, in pixel units, a maximum value of a value of third image
data, a value of fourth image data and a value of eighth image data, the
third image data is obtained by performing smoothing processing to second
image data for comparison representing the same image as the first image
data, the fourth image data is obtained by performing edge enhancement
processing to the second image data, the eighth image data is obtained by
respectively selecting a maximum value of values of neighboring plural
pixels for individual pixels of the second image data as values of those
pixels; andsetting, in the determination image, a preset third value for
pixels where a value of the sixth image data or the first image data is
equal to or less than a value of the seventh image data, or is equal to
or less than a sum of the value of the seventh image data and a preset
first value, and sets a value different from the third value for all
other pixels.

30. A storage medium storing a program to cause a computer to perform an
image processing, the image processing comprising:comparing, in pixel
units, tenth image data with seventh image data or second image
data;generating a determination image, wherein the tenth image data is
obtained by selecting, in pixel units, a minimum value of a value of
first image data of a determination target and a value of ninth image
data, the ninth image data is obtained by respectively selecting a
minimum value of values of neighboring plural pixels for individual
pixels of fifth image data obtained by performing edge enhancement
processing with respect to the first image data as values of those
pixels, the seventh image data are is by performing preset first
processing with respect to second image data for comparison representing
the same image as the first image data; andsetting, in the determination
image, a preset third value for pixels where the value of the tenth image
data is equal to or less than a value of the seventh image data or the
second image data, or is equal to or less than a sum of the value of the
seventh image data or the second image data and a preset first value, and
sets a value different from the third value for all other pixels.

31. A storage medium storing a program to cause a computer to perform an
image processing, the image processing comprising:comparing, in pixel
units, sixth image data or first image data with seventh image data or
second image data;generating a determination image, wherein the sixth
image data is obtained by performing preset second processing with
respect to first image data of a determination target, the seventh image
data is obtained by performing preset first processing with respect to
second image data for comparison representing the same image as the first
image data; andsetting, in the determination image, a preset third value
for first pixels where a value of the sixth image data or the first image
data is equal to or less than a value of the seventh image data or the
second image data, or is equal to or less than a sum of a value of the
seventh image data or the second image data and a preset first value, and
for second pixels where a value of third image data obtained by
performing smoothing processing to the second image data is equal to or
greater than a sum of the value of the second image data and a preset
sixth value and where a value of fourth image data obtained by performing
edge enhancement processing to the second image data is smaller than a
preset seventh value, and sets a value different from the third value for
all other third pixels.

32. A storage medium storing a program to cause a computer to perform an
image processing, the image processing comprising:comparing, in pixel
units, determination target first image data and second image data for
comparison representing the same image as the first image data;generating
a determination image; andsetting, in the determination image, a preset
third value for pixels where the value of the first image data is equal
to or less than the value of the second image data, or is equal to or
less than the sum of the value of the second image data and a preset
first value, and for pixels where the value of the second image data is
equal to or less than a preset second value, and sets a value that is
different from the third value for all other pixels.

33. An image processing method for operating an image processing
apparatus, the method comprising:comparing, in pixel units, sixth image
data with seventh image data or second image data;generating a
determination image, wherein the sixth image data is obtained by
selecting, in pixel units, a minimum value of a value of first image data
of a determination target and a value of fifth image data obtained by
performing edge enhancement processing to the first image data, the
seventh image data is obtained by performing preset first processing with
respect to second image data for comparison representing the same image
as the first image data; andsetting in the determination image a preset
third value for pixels where a value of the sixth image data is equal to
or less than a value of the seventh image data or the second image data,
or is equal to or less than a sum of the value of the seventh image data
or the second image data and a preset first value, and sets a value
different from the third value for all other pixels.

34. An image processing method for operating an image processing
apparatus, the method comprising:comparing, in pixel units, sixth image
data or first image data with seventh image data;generating a
determination image, wherein the sixth image data is obtained by
performing preset second processing with respect to first image data of a
determination target,the seventh image data is obtained by selecting, in
pixel units, a maximum value of a value of third image data, a value of
fourth image data and a value of eighth image data,the third image data
is obtained by performing smoothing processing to second image data for
comparison representing the same image as the first image data, the
fourth image data is obtained by performing edge enhancement processing
to the second image data, the eighth image data is obtained by
respectively selecting a maximum value of values of neighboring plural
pixels for individual pixels of the second image data as values of those
pixels; andsetting, in the determination image, a preset third value for
pixels where a value of the sixth image data or the first image data is
equal to or less than a value of the seventh image data, or is equal to
or less than a sum of the value of the seventh image data and a preset
first value, and sets a value different from the third value for all
other pixels.

35. An image processing method for operating an image processing
apparatus, the method comprising:comparing, in pixel units, tenth image
data with seventh image data or second image data;generating a
determination image, wherein the tenth image data is obtained by
selecting, in pixel units, a minimum value of a value of first image data
of a determination target and a value of ninth image data, the ninth
image data is obtained by respectively selecting a minimum value of
values of neighboring plural pixels for individual pixels of fifth image
data obtained by performing edge enhancement processing with respect to
the first image data as values of those pixels, the seventh image data
are is by performing preset first processing with respect to second image
data for comparison representing the same image as the first image data;
andsetting, in the determination image, a preset third value for pixels
where the value of the tenth image data is equal to or less than a value
of the seventh image data or the second image data, or is equal to or
less than a sum of the value of the seventh image data or the second
image data and a preset first value, and sets a value different from the
third value for all other pixels.

36. An image processing method for operating an image processing
apparatus, the method comprising:comparing, in pixel units, sixth image
data or first image data with seventh image data or second image
data;generating a determination image, wherein the sixth image data is
obtained by performing preset second processing with respect to first
image data of a determination target, the seventh image data is obtained
by performing preset first processing with respect to second image data
for comparison representing the same image as the first image data;
andsetting, in the determination image, a preset third value for first
pixels where a value of the sixth image data or the first image data is
equal to or less than a value of the seventh image data or the second
image data, or is equal to or less than a sum of a value of the seventh
image data or the second image data and a preset first value, and for
second pixels where a value of third image data obtained by performing
smoothing processing to the second image data is equal to or greater than
a sum of the value of the second image data and a preset sixth value and
where a value of fourth image data obtained by performing edge
enhancement processing to the second image data is smaller than a preset
seventh value, and sets a value different from the third value for all
other third pixels.

37. An image processing method for operating an image processing
apparatus, the method comprising:comparing, in pixel units, determination
target first image data and second image data for comparison representing
the same image as the first image data;generating a determination image;
andsetting, in the determination image, a preset third value for pixels
where the value of the first image data is equal to or less than the
value of the second image data, or is equal to or less than the sum of
the value of the second image data and a preset first value, and for
pixels where the value of the second image data is equal to or less than
a preset second value, and sets a value that is different from the third
value for all other pixels.

38. The image processing apparatus according to claim 4, wherein the
generator comprises a first smoothing processor that performs smoothing
processing with respect to the first image data, and the generator uses
the sixth image data obtained from the first image data to which the
smoothing processing has been performed for the comparison of image data
in pixel units and the generation of the determination image.

39. The image processing apparatus according to claim 5, wherein the
generator comprises a first smoothing processor that performs smoothing
processing with respect to the first image data, and the generator uses
the tenth image data obtained from the first image data to which the
smoothing processing has been performed for the comparison of image data
in pixel units and the generation of the determination image.

40. The image processing apparatus according to claim 39, wherein the
generator comprises a second smoothing processor that performs smoothing
processing with respect to the second image data using, as a unit, a
local region that is smaller than a local region in the smoothing
processing with respect to the first image data, and the generator uses
the seventh image data obtained from the second image data to which the
smoothing processing has been performed for the comparison of image data
in pixel units and the generation of the determination image.

41. The image processing apparatus according to claim 8, wherein the
generator comprises a second smoothing processor that performs smoothing
processing with respect to the second image data using, as a unit, a
local region that is smaller than a local region in the smoothing
processing with respect to the first image data, and the generator uses
the seventh image data obtained from the second image data to which the
smoothing processing has been performed for the comparison of image data
in pixel units and the generation of the determination image.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001]This application is based on and claims priority under 35 USC 119
from Japanese Patent Application Nos. 2009-211090 and 2010-064559,
respectively filed on Sep. 11, 2009 and Mar. 19, 2010.

[0005]Conventionally, there have been proposed technologies that check for
moire in an image of a printing target.

SUMMARY

[0006]An aspect of the present invention is an image processing apparatus
including a generator that compares, in pixel units, sixth image data
with seventh image data or second image data, and generates a
determination image, wherein the sixth image data is obtained by
selecting, in pixel units, a minimum value of a value of first image data
of a determination target and a value of fifth image data obtained by
performing edge enhancement processing to the first image data, the
seventh image data is obtained by performing preset first processing with
respect to second image data for comparison representing the same image
as the first image data, and the generator sets in the determination
image a preset third value for pixels where a value of the sixth image
data is equal to or less than a value of the seventh image data or the
second image data, or is equal to or less than a sum of the value of the
seventh image data or the second image data and a preset first value, and
sets a value different from the third value for all other pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]Exemplary embodiments of the present invention will be described in
detail based on the following figures, wherein:

[0008]FIG. 1 is a block diagram showing the general configuration of a
printing system pertaining to the exemplary embodiments;

[0009]FIG. 2 is a general configuration diagram of an image formation
apparatus;

[0010]FIG. 3 is a functional block diagram of a printing server pertaining
to a first exemplary embodiment;

[0011]FIGS. 4A and 4B are flowcharts showing a flow of moire determination
processing pertaining to the first exemplary embodiment;

[0012]FIG. 5A is a line graph describing the extraction of a moire
component in the generation of a determination image, and FIG. 5B is a
line graph describing the removal of an edge component;

[0013]FIG. 6 is a functional block diagram of a printing server pertaining
to a second exemplary embodiment;

[0014]FIGS. 7A and 7B are flowcharts showing a flow of moire determination
processing pertaining to the second exemplary embodiment;

[0015]FIG. 8 is a functional block diagram of a printing server pertaining
to a third exemplary embodiment;

[0016]FIG. 9 is a flowchart showing a flow of moire determination
processing pertaining to the third exemplary embodiment;

[0017]FIG. 10 is a line graph showing an example of change in each set of
data in an edge portion of a photo image when the moire determination
processing pertaining to the first and second exemplary embodiments has
been performed with respect to a photo image;

[0018]FIG. 11 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in the moire determination
processing pertaining to the third exemplar embodiment;

[0019]FIG. 12 is a line graph showing an example of change in each set of
data in an edge portion of a photo image when a minimum value of
descreened data and edge-enhanced descreened data are used in the moire
determination processing pertaining to the third exemplary embodiment;

[0020]FIG. 13 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in a case in which the value of
a determination image=0 when smoothed printer data≧descreened
data+threshold value Th4 in the moire determination processing pertaining
to the third exemplary embodiment;

[0021]FIG. 14 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in another aspect using smoothed
printer data;

[0022]FIG. 15 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in the other aspect using
smoothed printer data;

[0023]FIG. 16 is a functional block diagram of a printing server
pertaining to a fourth exemplary embodiment;

[0024]FIG. 17 is a flowchart showing a flow of moire determination
processing pertaining to the fourth exemplary embodiment;

[0025]FIG. 18 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in the moire determination
processing pertaining to the fourth exemplary embodiment;

[0026]FIG. 19 is a line graph showing an example of change in each set of
data in an edge portion of a photo image when a maximum value of
neighboring N pixels of printer data is used in the moire determination
processing pertaining to the fourth exemplary embodiment;

[0027]FIG. 20 is a line graph for describing erroneous extraction of moire
pixels resulting from noise superimposed on descreened data and printer
data;

[0028]FIG. 21 is a line graph diagram showing an example of change in each
set of data in a portion whose density is substantially uniform in the
moire determination processing pertaining to the fourth exemplary
embodiment;

[0029]FIG. 22 is a line graph showing an example of change in each set of
data in a portion whose density is substantially uniform, when a maximum
value of neighboring N pixels of printer data is used in the moire
determination processing pertaining to the fourth exemplary embodiment;

[0030]FIG. 23 is a functional block diagram of a printing server
pertaining to a fifth exemplary embodiment;

[0031]FIG. 24 is a flowchart showing a flow of moire determination
processing pertaining to the fifth exemplary embodiment;

[0032]FIG. 25 is a line graph showing an example of change in each set of
data in an edge portion of a photo image in the moire determination
processing pertaining to the fifth exemplary embodiment;

[0033]FIG. 26 is a line graph showing one example of change in each set of
data in an edge portion of a photo image when a minimum value of
neighboring N pixels of enhancement-processed descreened data is used in
the moire determination processing pertaining to the fifth exemplary
embodiment;

[0034]FIG. 27 is a line graph showing an example of change in each set of
data in a portion whose density is substantially uniform in the moire
determination processing pertaining to the fifth exemplary embodiment;
and

[0035]FIG. 28 is a line graph showing an example of change in each set of
data in a portion whose density is substantially uniform, when a minimum
value of neighboring N pixels of enhancement-processed descreened data is
used in the moire determination processing pertaining to the fifth
exemplary embodiment.

DETAILED DESCRIPTION

First Exemplary Embodiment

[0036]FIG. 1 shows a printing system 10 pertaining to the exemplary
embodiments. The printing system 10 includes an image formation apparatus
12, which functions as a printer that forms a visible color image on
recording paper by an electrophotographic process on the basis of
inputted print image data, and a plate making apparatus (CTP: Computer To
Plate) 24, which directly creates printing plates for performing printing
in a printing machine (a press) 22 from inputted print image data. The
image formation apparatus 12 is connected to a printing server 26 via a
communication line. The printing server 26 is connected to the plate
making apparatus 24 and plural terminal devices 36 via a communication
line 46.

[0037]The image formation apparatus 12 includes a main controller 14 that
has built therein a CPU 14A formed of a microcomputer or the like, a
memory 14B, a nonvolatile storage unit 14C formed of a hard disk drive
(HDD) or a flash memory, and a communication interface unit 14D. The
image formation apparatus 12 is connected to the printing server 26 via
the communication interface unit 14D. An image printing section 16 that
prints an image represented by inputted print image data on recording
paper and an operation panel 18 in which are disposed a display unit 18A
formed of an LCD or the like and an operation unit 18B formed of a
numerical keypad and a touch panel or the like are connected to the main
controller 14.

[0038]As shown in FIG. 2, the image printing section 16 includes an image
formation module 60, a feeder module (FM) 64 that feeds recording paper
to the image formation module 60, a connecting module 66 that
interconnects the image formation module 60 and the feeder module 64, and
an output module 68 that discharges, to the outside, recording paper on
which an image has been formed by the image formation module 60. The
feeder module 64 may have a multistage configuration. A finisher module
may also be disposed downstream of the output module 68. Examples of the
finisher module may include a finisher module including a stapler that
stacks sheets of the recording paper and binds the sheets in one place in
a corner portion of the stack or in two or more places along one edge of
the stack, and a finisher module including a punching mechanism that
punches punch holes for filing. The finisher module may also be used in
an offline state where the image formation apparatus 12 is not connected
via a communication line to another device.

[0039]The image formation module 60 includes an image formation core unit
70 and a toner supply unit 72. Toner cartridges 74 of the four colors of
C, M, Y, K are loaded into the toner supply unit 72. The image formation
core unit 70 includes four print engines (printing units) 76
corresponding to each color component of C, M, Y, K. The print engines 76
are arranged in one row along the direction of rotation of an endless
intermediate transfer belt 88 (i.e., arranged in a tandem arrangement).
Each of the print engines 76 includes a photoconductor drum 78, a charger
80 that charges the photoconductor drum 78, an optical scanner 82 that
forms an electrostatic latent image on the photoconductor drum 78 by
scanning the photoconductor drum 78 with a light beam modulated in
accordance with printing data of the corresponding color component, a
developing device 84 that develops the electrostatic latent image formed
on the photoconductor drum 78 to thereby form a toner image, and a
primary transfer device 86 that transfers (primarily transfers) the toner
image formed on the photoconductor drum 78 onto the intermediate transfer
belt 88. The toner images of each color component that have been formed
by the individual print engines 76 are superimposed on each other on the
intermediate transfer belt 88, whereby a color toner image is formed on
the intermediate transfer belt 88.

[0040]The color toner image that has been formed on the intermediate
transfer belt 88 is transferred (secondarily transferred) by a secondary
transfer device 90 onto the recording paper that has been conveyed from
the feeder module 64 at a predetermined timing. The recording paper onto
which the color toner image has been transferred is conveyed along a
conveyance path 92 to a fuser 94, the toner image is fused and fixed to
the recording paper by the fuser 94, and the recording paper is delivered
to a paper discharger 96 of the output module 68 (the recording paper may
be delivered to the paper discharger 96 after being held temporarily in a
paper discharge unit (a stacker) 98) and is discharged to the outside
after final processing has been performed as needed. When two-sided
printing is performed, the recording paper to whose one side the toner
image has been fixed (on whose one side the color image has been printed)
is again fed from the paper discharge unit 98 to the conveyance path 92
in an inverted state via an inversion path 100 and an inversion
conveyance path 102 of the image formation module 60. The image formation
core unit 70 also includes an electrical system control housing unit 104
that houses electric circuits that control the operation of the
individual print engines 76 and power supply circuits for each module.

[0041]Although detailed description will be omitted, the plate making
apparatus 24 may employ a configuration that makes a printing plate
(plate) of a particular color component by, for example, wrapping a
sheet-like printing plate around, and fixing the sheet-like printing
plate to, the outer peripheral surface of a cylindrical rotating drum,
recording an image on the printing plate by causing the rotating drum to
rotate and irradiating the printing plate integrally rotating with the
rotating drum with a light beam modulated in accordance with inputted
printing data of a particular color component, and thereafter developing
the printing plate on which the image has been recorded. In this case,
printing plates corresponding to each color component can be obtained by
repeating the above-described process in regard to each color component
of C, M, Y, K. The printing plates of each color component that have been
made by the plate making apparatus 24 are set in the printing machine 22
and used for printing.

[0042]In the printing system 10, a user can instruct printing online from
the terminal device 36 with respect to the image formation apparatus 12
and the plate making apparatus 24. Moreover, the user can select whether
to perform printing using the image formation apparatus 12 or whether to
perform printing using the plate making apparatus 24 (i.e., to make a
printing plate with the plate making apparatus 24, set in the printing
machine 22 the printing plate that has been made, and perform printing).
In printing using the image formation apparatus 12, work such as creating
a printing plate and setting the created printing plate in the printing
machine is unnecessary, and printing is completed in a short amount of
time after instructing printing (the printing speed is about 60 sheets
per minute). However, there is a limit on the size of printable recording
paper (ordinarily A3 size or smaller), so the image formation apparatus
12 is utilized when printing a relatively small quantity of plural types
of printed matter of a predetermined size or smaller. Further, the image
formation apparatus 12 is also utilized when the user desires to check an
image represented by print image data used for making a printing plate
prior to the plate making by the plate making apparatus 24. In printing
using the plate making apparatus 24, the plate making by the plate making
apparatus 24 takes a relatively long amount of time (e.g., about several
minutes per one printing plate), and it also takes effort to set in the
printing machine the printing plate that has been made. However, printing
can be performed at a high speed (e.g., several hundred sheets per
minute) once the printing plate is set into the printing machine, and the
limit on the size of printed matter is also lenient. For that reason, the
plate making apparatus 24 is utilized when printing large-size printed
matter or when printing a large quantity of a few types of printed
matter.

[0043]The terminal device 36 may be a personal computer (PC) and includes
a main device 38 that has built therein a CPU 38A, a memory 38B, a
nonvolatile storage unit 38C formed of a HDD or a flash memory, and a
communication interface unit 38D. The main device 38 is connected to the
communication line 46 via the communication interface unit 38D. A display
40, a keyboard 42 and a mouse 44 are connected to the main device 38. An
operating system (OS) and application software for creating a printing
target document are installed in the storage unit 38C.

[0044]In the present exemplary embodiment, the user may create a printing
target document by operating the terminal device 36 and utilizing the
application software. This document may be a text document, an image such
as a photograph or a graphic, or a document in which text and images are
mixed. When creation of the printing target document is completed, the
user may perform an operation that instructs printing of the printing
target document. In this operation, parameters stipulating the type (the
image formation apparatus 12 or the printing machine 24) of printing
device and printing conditions such as the number of prints to be made
and the size and the paper quality of the printed matter are also
designated. When this operation is performed by the user, printing
control information (data) that represents, in a predetermined format
(e.g., job definition format (JDF)), the printing conditions that have
been set by the user is generated. The generated printing control data is
transmitted from the terminal device 36 to the printing server 26
together with printing data in which the printing target document is
described by page description language (PDL).

[0045]Next, the printing server 26 will be described. The printing server
26 includes a server device 28 that has built therein a CPU 28A, a memory
28B, a nonvolatile storage unit 28C formed of a HDD or a flash memory,
and a communication interface unit 28D. The printing server 26 is
connected to the communication line 46 via the communication interface
unit 28D. A display 30, a keyboard 32 and a mouse 34 are connected to the
server device 28. A printing data generation program for causing the
printing server 26 to function as a print image data generator 50 (see
FIG. 3; described later) and a moire determination program (for
performing later-described moire determination processing with the CPU
28A) for causing the printing server 26 to function as a moire
determination unit 110 (see FIG. 3; described later) are installed in the
storage unit 28C.

[0046]As shown in FIG. 3, the print image data generator 50, which is
realized as a result of the printing data generation program being
executed by the CPU 28A, includes a data storage unit 52, a RIP processor
for plate making (plate making RIP processor) 54A, a RIP processor for
printer (printer RIP processor) 54B, an image processor 56, and interface
units 58A and 58B. Printing data (that are described by PDL and whose
colors are expressed by R, B) that the printing server 26 has received
from the terminal device 36 are sequentially stored in the data storage
unit 52. A PDL interpreter and a RIP engine are incorporated in each of
the RIP processors 54A and 54B.

[0047]The print image data generator 50 recognizes the type of printing
device (the plate making apparatus 24 or the image formation apparatus
12) by referencing the printing control data. When the recognized device
type is the plate making apparatus 24, the plate making RIP processor 54A
is activated, and when the recognized device type is the image formation
apparatus 12, the printer RIP processor 54B is activated. When the plate
making RIP processor 54A is activated, the RIP processor 54A retrieves
and interprets the printing data from the data storage unit 52 and
performs, in page units, color conversion from R, G, B to C, M, Y, K and
rendering into raster image data (bitmap data) by halftone dot
processing. Thus, the plate making RIP processor 54A performs raster
image (RIP) processing that generates print image data of a format usable
in printing by the plate making apparatus 24 (e.g., a binary/high
resolution format whose resolution is relatively high (e.g., 2400 dpi)
and which expresses 1 pixel (1 dot) by 1 bit of each of C, M, Y, K). In
the halftone dot processing by the plate making RIP processor 54A, a 175
line (175 lpi: 175 lines per inch) screen, for example, is used.

[0048]When the printer RIP processor 54B is activated, the RIP processor
54B retrieves and interprets the printing data from the data storage unit
52 and performs, in page units, color conversion from R, G, B to C, M, Y,
K and rendering into raster image data (bitmap data). Thus, the printer
RIP processor 54B performs RIP processing that generates print image data
of a format usable in printing by the image formation apparatus 12 (e.g.,
a multi-value/low resolution format whose resolution is relatively low
(e.g., 1600 dpi) and which expresses gradation of 1 pixel in plural bits
(e.g., 8 bits) of each of C, M, Y, K). When the later-described moire
determination processing is performed with respect to printing data where
the plate making apparatus 24 has been set as the type of printing
device, the RIP processors 54A and 54B are activated and RIP processing
is performed by the RIP processors 54A and 54B.

[0049]The RIP processors 54A and 54B reference the printing control data
corresponding to the printing data retrieved from the data storage unit
52, judge the printing conditions, and perform, together with RIP
processing, necessary image processing on the basis of the judged
printing conditions. Examples of image processing which may be performed
together with the RIP processing by the plate making-use RIP processing
54A include imposition, which assigns plural pages of images onto a
large-size printing surface corresponding to large-size recording paper.
Examples of image processing which may be performed together with the RIP
processing by the printer RIP processor 54B include rotation, assignment
of plural pages of images into one sheet of paper, repeat processing,
paper size fitting, color management system (CMS) processing that
corrects device differences, resolution conversion, and contrast
adjustment.

[0050]When RIP processing has been performed by the plate making RIP
processor 54A, the plate making RIP processor 54A outputs to the
interface unit 58A the print image data that have been obtained via the
above-described processing. In this case, the print image data are
sequentially transferred to the plate making apparatus 24 by the
interface unit 58A and are used in printing (creation of a printing
plate) by the plate making apparatus 24. When RIP processing has been
performed by the printer RIP processor 54B, the printer RIP processor 54B
outputs to the image processor 56 the print image data that have been
obtained via the above-described processing.

[0051]The image processor 56 references the printing control data
corresponding to the print image data that have been outputted to the
image processor 56 from the printer RIP processor 54B, judges the
printing conditions, and performs image processing corresponding to the
judged printing conditions. That is, the image processor 56 is equipped
with the function of performing various types of processing, such as
rotating images, adjusting image positions on sheets of paper, and
enlargement or reduction, with respect to the inputted print image data.
Depending on discharge conditions that are set in the printing control
data and on the structure and characteristics of the image formation
apparatus 12 that performs printing, the image processor 56 performs
various types of different processing such as rearranging pages in
ascending order or descending order, deciding the processing page order
at the time of two-sided printing, calibration processing such as color
conversion using a multidimensional lookup table, gray balance correction
and color shift correction, screen designation processing, page
rearrangement (stapler or punch hole place securement) corresponding to
finishing processing executed by the finisher module of the image
formation apparatus 12, collation, discharge surface (vertical)
alignment, etc. The print image data on which the various types of
processing have been performed by the image processor 56 are transferred
to the image formation apparatus 12 via the interface unit 58B and are
used in the printing by the image formation apparatus 12.

[0052]The moire determination unit 110, which is realized as a result of
the moire determination program being executed by the CPU 28A and
performs the moire determination processing described next, includes a
value multiplexer/resolution converter 112, pixel number adjusters 114A
and 114B, smoothing processors 116A and 116B, a determination-use image
generator 118, an enhancement processor 120, a color
separation/imposition processor 122, a moire pixel counter 124, and a
moire determination display unit 126. Processing by each functional block
configuring the moire determination unit 110 will be described later.

[0053]Next, an operation of the first exemplary embodiment will be
described. In the printing system 10, binary image data for plate making
(print image data used in printing by the plate making apparatus 24) are
generated as a result of RIP processing including halftone dot processing
being performed by the plate making RIP processor 54A on the basis of
printing data that the printing server 26 has received from the terminal
device 36. At this time, there is the potential for moire to occur in the
binary image data for plate making when a spatial frequency component
approximating the pitch of the screen (e.g., 175 lines per inch if it is
a 175 line screen) used in halftone dot processing or a spatial frequency
component that is higher than this pitch is included in the original
image (the image represented by the printing data).

[0054]In the present exemplary embodiment, the moire determination program
for determining whether or not moire is occurring in the binary image
data for plate making is stored in the storage unit 28C of the printing
server 26. When the user desires to check whether or not moire is
occurring in the binary image data for plate making, the user instructs
the printing server 26 to determine whether or not there is moire with
respect to the binary image data for plate making via the terminal device
36 before performing creation of a printing plate with the plate making
apparatus 24 using the binary image data for plate making that have been
generated. Using this instruction as a trigger, the printing server 26
performs the moire determination processing shown in FIGS. 4A and 4B by
executing the moire determination program by the CPU 28A.

[0055]In the moire determination processing, first, in step 150, the
processing acquires binary data for plate making (plate making binary
data), which is a target of the moire determination, from the plate
making RIP processor 54A. Then, the printer RIP processor 54B performs
RIP processing on the basis of the same printing data as the printing
data that was used to generate the plate making binary image data. The
processing acquires, from the printer RIP processor 54B, multi-value data
for printer (print image data usable in printing by the image formation
apparatus 12: an example of "comparison-use second image data") that have
been generated by this RIP processing.

[0056]In step 152, with respect to the target plate making binary data
acquired from the plate making RIP processor 54A in step 150, conversion
(descreening) to multi-value data that express gradations with plural
bits (e.g., 8 bits) for each of C, M, Y, K per one pixel and conversion
to a predetermined resolution are performed. When moire had occurred in
the target plate making binary data, the moire also remains in the data
after conversion regardless of the descreening. As the resolution, a
resolution of 1/n (n is an integer) with respect to the resolution of the
plate making binary data can be adopted. For example, if the resolution
of the plate making binary data is 2400 dpi, 600 dpi (n=4), 800 dpi (n=3)
or 1200 dpi (n=2) can be applied as the resolution. Taking into
consideration the precision of moire determination using a
later-described determination image, the resolution may preferably be
equal to or higher than 600 dpi in terms of practicality.

[0057]In step 154, a determination is made as to whether or not the
resolution of the printer multi-value data acquired from the printer RIP
processor 54B in step 150 matches the predetermined resolution (the
resolution of the data that have undergone the descreening and resolution
conversion of step 152). The data that have undergone the descreening and
resolution conversion of step 152 are an example of "first image data of
a determination target"; hereinafter, this data will be called descreened
data. When the determination of step 154 is positive, the processing
moves to step 158, but when the determination of step 154 is negative
(for example, when the predetermined resolution is 600 dpi, 800 dpi or
1200 dpi and the resolution of the printer multi-value data is 360 dpi or
720 dpi), the processing moves to step 156, where conversion to the
predetermined resolution is performed with respect to the printer
multi-value data.

[0058]In step 158, comparison of the numbers of vertical and horizontal
pixels in the printer multi-value data and the descreened data is made,
and when the numbers of pixels in both do not match, pixel number
adjustment processing is performed by which the numbers of vertical and
horizontal pixels in both are made to match by adding, in correspondence
to the amount by which the numbers of pixels are deficit, pixel rows of
white pixels where C, M, Y, K=0 to the data having the fewer number of
pixels of the printer multi-value data and the descreened data. Due to
step 154 to step 158, the resolution of, and the numbers of vertical and
horizontal pixels in, the printer multi-value data and the descreened
data are made to match.

[0059]In step 160, smoothing processing is performed with respect to the
descreened data and the printer multi-value data. This smoothing
processing can be realized, for example, by using a local mean filter to
perform averaging processing, which takes the mean value of all pixels in
a local region including a center pixel as the value of the center pixel
(other filters, such as a local weighted mean filter or a median filter,
may be used instead of a local mean filter). In the present exemplary
embodiment, the size (also called order) of the local mean filters used
in the smoothing processing with respect to the descreened data and the
smoothing processing with respect to the printer multi-value data are
different.

[0060]That is, since the plate making binary data are generated as a
result of RIP processing including halftone dot processing being
performed, there is the potential for dots whose maximum pitch is the
pitch on the descreened data of the screen used in halftone dot
processing and which repeatedly appear to remain as screen noise in the
descreened data. For this reason, in the present embodiment, the size of
the local mean filter used in the smoothing processing with respect to
the descreened data is larger than the pitch on the descreened data of
the screen used in the halftone dot processing (the size of the unit
region on the first image data) and smaller than the period of the moire
on the descreened data.

[0061]Specifically, assuming, for example, that the resolution of the
plate making binary data is 2400 dpi, the screen used in halftone dot
processing is 175 1pi, and the resolution of the descreened data is 600
dpi. In this case, the pitch on the descreened data of the screen is 3.4
pixels, and the period of the moire on the descreened data whose
resolution is 600 dpi is about 40 to 50 pixels. Therefore, for example, a
size of 5 pixels×5 pixels to 13 pixels×13 pixels may be used
as the local mean filter used in the smoothing processing with respect to
the descreened data. By using a local mean filter of this size, the moire
remaining in the descreened data is preserved while the screen noise
remaining in the descreened data is removed.

[0062]Further, by using a local mean filter of a relatively large size as
described above to perform the smoothing processing with respect to the
descreened data, the edge (precipitous value change) in the descreened
data also becomes dull. If the edge in the printer multi-value data is
also made dull by using a local mean filter of a relatively large size to
perform the smoothing processing also with respect to the printer
multi-value data, the resultant determination image may fluctuates in
generating the determination image which will be described later, such
that pixels corresponding to the edge being erroneously extracted or not
extracted as pixels corresponding to the moire. This is because of a
slight difference in the degree of dullness of the edge in the descreened
data and the degree of dullness of the edge in the printer multi-value
data.

[0063]For this reason, in the present exemplary embodiment, the size of
the local mean filter used in the smoothing processing with respect to
the printer multi-value data is made smaller than the size of the local
mean filter used in the smoothing processing with respect to the
descreened data. Specifically, for example, when the resolution of the
printer multi-value data is 600 dpi, a size of about 3 pixels×3
pixels is used as the local mean filter used in the smoothing processing
with respect to the printer multi-value data. Images in which significant
moire occur are often images such as photo images that have been captured
by a digital still camera. However, when a local mean filter of the size
described above is used to perform the smoothing processing with respect
to the printer multi-value data, noise caused by an imaging device such
as a CCD of the digital still camera is removed from the printer
multi-value data while the edge in the printer multi-value data is
preserved virtually without becoming dull.

[0064]In step 162 to step 180, generation of a determination image for
determining moire is performed using the descreened data and the printer
multi-value data that have undergone smoothing processing in step 160.
That is, first, in step 162, a variable n representing the position of a
processing target pixel in the image is initialized to 0. In step 164, a
value representing any of C, M, Y, K is set to a variable i representing
a processing target color. In step 166, a determination is made as to
whether or not there is a pixel in the pixel position (pixel position n)
represented by the variable n in the images represented by the descreened
data and the printer multi-value data.

[0065]When the determination is positive, the processing moves to step
168, where a determination is made as to whether or not a value Cn1i of
color i of the pixel in pixel position n of the printer multi-value data
is 0 (a second value). When this determination is negative, the program
moves to step 170, where a determination is made as to whether or not the
sum of the value Cn1i and a preset determination threshold value Th0 (a
first value) is smaller than a value Dn1i of color i of the pixel in
pixel position n of the descreened data. When the determination of step
168 is positive or when the determination of step 170 is negative, the
program moves to step 172, in which a value Oni of color i of the pixel
in pixel position n in the determination image is set to 0 (a third
value), and then the processing moves to step 176. When the determination
of step 170 is positive, the program moves to step 174, in which the
difference between the value Dn1i and both the value Cn1i and the
determination threshold value Th0 (i.e., a value corresponding to the
difference between the value of the first image data and the value of the
second image data) is set as the value Oni, and then the processing moves
to step 176.

[0066]In step 176, a determination is made as to whether or not it the
processings of step 168 to step 174 have been performed with respect to
all colors of C, M, Y, K of the pixel in pixel position n. When the
determination is negative, the processing moves to step 178, where a
value representing the unprocessed color of C, M, Y, K is set for the
variable i. When after step 178, the processing returns to step 168 and
repeats step 168 to step 178 until the determination of step 176 becomes
positive. When step 168 to step 174 are performed with respect to all
colors of C, M, Y, K of the pixel in pixel position n, the determination
of step 176 is positive and the processing moves to step 180, where the
variable n is updated (e.g., increments by 1), and thereafter the
processing returns to step 164. Thus, step 164 to step 180 are repeated
until the determination of step 166 becomes negative, and the processing
of step 168 to step 174 is performed per each color of C, M, Y, K in
regard to all pixels in the image represented by the descreened data and
in the image represented by the printer multi-value data.

[0067]The processing of step 168 to step 174 will be further described
with reference to FIG. 5A and FIG. 5B. As mentioned earlier, moire of the
plate making binary image data occurs in the RIP processing including
halftone dot processing being performed by the plate making RIP processor
54A. When moire had occurred in the original plate making binary image
data, the moire also remains in the descreened data generated from the
plate making binary data. However, so moire does not occur in the printer
multi-value data because halftone dot processing is not performed on the
printer multi-value data in the RIP processing performed by the printer
RIP processor 54B, and the resolution of the printer multi-value data
also differs from that of the plate making binary image data. For this
reason, when moire remains in the descreened data, in the images
represented by the descreened data and the printer multi-value data, in a
region where the value of each pixel is constant or where the change in
the value of each pixel is small, as shown in FIG. 5A, each pixel of the
printer multi-value data shows an approximately constant value while the
value of each pixel of the descreened data shows a change where it
fluctuates periodically because of the remaining moire.

[0068]In the processing of step 168 to step 174, when the value Dn1i of
the descreened data is equal to or less than the sum of the value Cn1i of
the printer multi-value data and the determination threshold value Th0
(when the determination of step 170 is negative), the value Oni of the
determination image is set to 0 (step 172). Further, when the value Dn1i
is larger than the sum of the value Cn1i and the threshold value Th0
(when the determination of step 170 is positive), the difference between
the value Dn1i and both the value Cn1i and the threshold value Th0 is set
as the value Oni (step 174). Thus, as will also be understood from FIG.
5A, the moire component superimposed on the descreened data is extracted
as the determination image. Further, since the value Dn1i is compared
with the sum of the value Cn1i and the threshold value Th0, even if noise
were to remain without being removed from the descreened data and the
printer multi-value data regardless of smoothing processing, adverse
affects resulting from this noise are alleviated.

[0069]Further, because the smoothing processing with respect to the
descreened data is performed using a local mean filter of a relatively
large size, as shown in FIG. 5B, the change in the value of each pixel of
the descreened data in the portion corresponding to the edge in the image
is dulled. In contrast, because a local mean filter of a smaller size
than that for the descreened data is used for the smoothing processing
with respect to the printer multi-value data, as shown in FIG. 5B, the
value of each pixel of the printer multi-value data changes more
precipitously than the descreened data in the portion corresponding to
the edge in the image.

[0070]With respect thereto, in the processing of step 168 to step 174,
when the value Cn1i is 0 (when the determination of step 168 is
positive), the value Oni is set to 0 (step 172). For that reason, as
shown by the hatching indicated by dotted lines in FIG. 5B, the portion
(edge component) corresponding to the edge in the image where the value
Dn1i is larger than the value Cn1i is removed from the determination
image. Consequently, due to the processing of step 168 to step 174, per
each color of C, M, Y, K, a determination image is obtained in which a
value corresponding to the amplitude of the moire component has been set
only for pixels (moire pixels) corresponding to moire occurring in the
plate making binary image data and remaining in the descreened data, and
the value has been set to 0 for pixels other than the moire pixels.

[0071]When the processing of step 168 to step 174 in regard to each color
of C, M, Y, K of all pixels in the image represented by the descreened
data and in the image represented by the printer multi-value data is
completed and the determination image is generated, the determination of
step 166 is negative and the processing moves to step 182. In step 182,
the value of each color of C, M, Y, K of each pixel in the determination
image is compared with a preset determination threshold value Th1 the
number of pixels where any value of each color of C, M, Y, K of each
pixel in the determination image is equal to or greater than the
threshold value Th1 is counted as the number of moire pixels whose
potential to correspond to moire is high.

[0072]In step 184, the result of counting the moire pixels in step 182
(the number of moire pixels) is compared with a preset determination
threshold value Th2 to determine whether or not there is moire on the
basis of whether or not the number of moire pixels is equal to or greater
than the threshold value Th2. Then, the result of moire determination is
transmitted to the terminal device 36 from which the instruction of the
moire determination came, and the result is displayed on the display 40
of the terminal device 36. Thus, whether or not moire will occur when the
target plate making binary data have been used to perform printing plate
creation and printing is recognized by the user. Instead of displaying
the result of the moire determination on the display 40 of the terminal
device 36, the display may be performed on the display 30 of the printing
server 26.

[0073]In the steps subsequent to step 186, processing of visualizing the
determination image is performed. As is apparent from FIG. 5A and FIG.
5B, the values of the moire pixels in the determination image are valued
corresponding to deviations between the descreened data and the printer
multi-value data--that is, values corresponding to the amplitude of the
moire component. For that reason, even if the determination image is
visualized as is, it would be difficult to view the moire pixels and
checking of the moire would be difficult. Therefore, in step 186, a
histogram of the determination image is generated, and in step 188, on
the basis of the histogram generated in step 186, the degree of
enhancement of the determination image (a coefficient with which the
value of each color of each pixel in the determination image is
multiplied) is determined such that the maximum value of the moire pixels
in the determination image is converted to a maximum value that can be
taken in the data of the determination image (e.g., 255 if the data are
data that allocate 8 bits for each C, M, Y, K per one pixel).

[0074]In step 190, enhancement processing that increases the difference of
the value of each color of each pixel in the determination image is
performed by multiplying the degree of enhancement (coefficient)
determined in step 188 with the value of each color of each pixel in the
determination image. Thus, a visible (easy-to-see) determination image
(which will be called determination image A) is obtained on which the
result of extracting the moire pixels per each color of C, M, Y, K is
superimposed.

[0075]In step 192, the determination image A obtained through enhancement
processing is separated into determination images per each color of C, M,
Y, K and reduces the determination images per each color of C, M, Y, K
(four pages of determination images) by a reduction ratio with which the
determination images are imposable on a single page. In step 194, a
determination image B in which the determination images per each color
reduced in step 192 are imposed on a single page is generated (i.e., a
single image in which the determination images per each color to which
enhancement processing has been administered are reduced and arrayed is
generated). In step 196, the data of determination image A, the data of
determination image B and the data of the original image (e.g., the
printer multi-value data or the like are used) are transmitted to the
terminal device 36 from which the instruction of the moire determination
came, and the determination image A, the determination image B and the
original image are displayed on the display 40 of the terminal device 36.

[0076]For example, if the image represented by the descreened data is
displayed on the display to check for moire, it would be difficult to
display at one time the entire image represented by the descreened data
with the same resolution as the resolution during printing using a
printing plate. In this case, a user would have to repeatedly display a
part of the image represented by the descreened data on the display and
check for moire in the displayed part, while scrolling over the part of
the image represented by the descreened data that is displayed on the
display. Further, since the principle of displaying an image on a display
is completely different from that of printing an image using a printing
plate, even if the image represented by the descreened data is displayed
as is on a display, the visibility of the moire would be significantly
lower than in an image that has been printed using a printing plate.

[0077]In contrast, the determination image A is an image where the moire
component has been extracted from the descreened data and to which
enhancement processing has been performed. Therefore, even when the
entire determination image A is reduced and displayed on a display, the
moire component superimposed on the descreened data is clearly displayed
without being affected by resolution, output scale factor or differences
in principles of image output. Further, when a region where moire of
plural colors is superimposed had existed in the image, the clarity of
display of the moire component in that region drops on the determination
image A. However, since the determination image B is configured such that
the determination images per each color of C, M, Y, K being imposed on a
single page, moire of plural colors in that region is separated per each
color and displayed in the determination image per each color configuring
the determination image B.

[0078]In step 198, a determination is made as to whether or not printing
of a determination image or the like has been instructed. When the
determination is negative, the moire determination processing is
terminated. When the determination of step 198 is positive as a result of
printing of a determination image or the like being instructed by the
user via the terminal device 36, the processing moves to step 200. In
step 200, the data of the determination image A, the data of the
determination image B and the data of the original image is transmitted
to the image formation apparatus 12 via the interface unit 58B, the
determination image A, the determination image B and the original image
are printed on recording paper by the image formation apparatus 12, and
thereafter the moire determination processing is terminated.

[0079]For example, when the image represented by the descreened data is
printed on a recording paper by the image formation apparatus 12, the
principle of printing, the printing agent, and the resolution differ from
those in the printing of an image using a printing plate. For that
reason, the visibility of moire in the image that has been printed on a
recording paper by the image formation apparatus 12 is significantly
lower than that in an image that has been printed using a printing plate.
In contrast, the determination image A is, as mentioned earlier, an image
where the moire component has been extracted from the descreened data and
to which enhancement processing has been performed. Therefore, even when
this determination image A is printed on a recording paper by the image
formation apparatus 12, the moire component superimposed on the
descreened data is clearly displayed without being affected by
differences in the principle of printing, the printing agent or
resolution. Further, even if a region where moire of plural colors is
superimposed had existed in the image, the moire of plural colors in that
region is separated per each color and displayed on the determination
images per each color of the determination image B that has been printed
on recording paper by the image formation apparatus 12.

Second Exemplary Embodiment

[0080]Next, a second exemplary embodiment will be described. The same
reference numerals will be given to portions that are the same as those
in the first exemplary embodiment, and description thereof will be
omitted. As shown in FIG. 6, the moire determination unit 110 pertaining
to the second exemplary embodiment differs from the moire determination
unit 110 of the first exemplary embodiment in that it includes an edge
enhancement processor 128. The printer multi-value data outputted from
the pixel number adjuster 114A and printer multi-value data outputted
from the edge enhancement processor 128 are also inputted to the
determination image generator 118, as well as the printer multi-value
data outputted from the smoothing processor 116A and the descreened data
outputted from the smoothing processor 116B.

[0081]Only those portions of the moire determination processing pertaining
to the second exemplary embodiment that differ from the moire
determination processing described in the first exemplary embodiment
(FIGS. 4A and 4B) will be described with reference to FIGS. 7A and 7B. In
the moire determination processing of the second exemplary embodiment,
after the smoothing processing is performed in step 160 with respect to
the printer multi-value data and the descreened data that have undergone
the pixel number adjustment processing, in step 161, edge enhancement
processing is performed with respect to the printer multi-value data
subjected to the pixel number adjustment processing. In the second
exemplary embodiment, the printer multi-value data that have undergone
the smoothing processing of step 160 will hereinafter be called "smoothed
printer multi-value data" (third image data).

[0082]The edge enhancement processing in step 161 can be realized by
processing such as using an edge extraction filter such as a differential
filter, for example, to extract the edge component from the printer
multi-value data that have undergone pixel number adjustment processing,
multiplying the extracted edge component with a preset coefficient, and
adding the product to the original printer multi-value data. Thus, image
data is obtained where the edge has been enhanced with respect to the
printer multi-value data that have undergone pixel number adjustment
processing. The printer multi-value data that have undergone the edge
enhancement processing of step 161 will hereinafter be called
"edge-enhanced printer multi-value data" (fourth image data).

[0083]Further, in the moire determination processing of the second
exemplary embodiment, in step 168, a determination is made as to whether
or not the value Cn1i of color i of the pixel in pixel position n of the
printer multi-value data that have undergone pixel number adjustment
processing (the printer multi-value data that are outputted from the
pixel number adjuster 114A in FIG. 6) is 0. When the determination is
negative, the processing moves to step 169, where the maximum value of
the value Cn1i of color i of the pixel in pixel position n of the printer
multi-value data, a value Cn2i of color i of the pixel in pixel position
n of the smoothed printer multi-value data and a value Cn3i of color i of
the pixel in pixel position n of the edge-enhanced printer multi-value
data is set to a determination reference value Cm. In step 171, a
determination is made as to whether or not the sum of a determination
reference value Cm and the determination threshold value Th0 is smaller
than the value Dn1i of color i of the pixel in pixel position n of the
descreened data.

[0084]When the determination of step 168 is positive or the determination
of step 171 is negative, the processing moves to step 172, where the
value Oni of color i of the pixel in pixel position n in the
determination image is set to 0, and then the processing moves to step
176. When the determination of step 171 is positive, the processing moves
to step 175, where the difference between the value Dn1i and both the
value Cn2i and the threshold value Th0 (i.e., a value corresponding to
the difference between the value of the first image data and the value of
the third image data) is set as the value Oni, and then the processing
moves to step 176. Processing from step 176 on is the same as that in the
moire determination processing of the first exemplary embodiment (FIGS.
4A and 4B), so description thereof will be omitted.

[0085]In the moire determination processing pertaining to the second
exemplary embodiment (FIGS. 7A and 7B), as mentioned above, the
difference between the value Dn1i and both the value Cn2i and the
threshold value Th0 is set as the value Oni of the determination image
only when the value Dn1i of the descreened data is larger than the sum of
the threshold value Th0 and the maximum value (the determination
reference value Cm) of the value Cn1i of the printer multi-value data,
the value Cn2i of the smoothed printer multi-value data and the value
Cn3i of the edge-enhanced printer multi-value data. For that reason, the
edge component is removed with better precision from the determination
image in comparison to the moire determination processing described in
the first exemplary embodiment.

Third Exemplary Embodiment

[0086]Next, a third exemplary embodiment of the present invention will be
described. The same reference numerals will be given to portions that are
the same as those in the second exemplary embodiment, and description of
those same portions will be omitted. As shown in FIG. 8, the moire
determination unit 110 pertaining to the third exemplary embodiment
differs from the moire determination unit 110 described in the second
exemplary embodiment in that an edge enhancement processor 130 and a
noise remover 132 are added. Descreened data that have been outputted
from the edge enhancement processor 130 are also inputted to the
determination image generator 118, as well as the printer multi-value
data outputted from the pixel number adjuster 114A, the printer
multi-value data outputted from the smoothing processor 116A, the printer
multi-value data outputted from the edge enhancement processor 128 and
the descreened data outputted from the smoothing processor 116B.
Moreover, the determination image that has been generated by the
determination image generator 118 undergoes noise removal processing by
the noise remover 132 and is outputted to the enhancement processor 120
and the moire pixel counter 124.

[0087]Next, an operation of the third exemplary embodiment will be
described. As mentioned above, there is a potential for moire to occur in
the plate making binary data generated from the printing data by RIP
processing (e.g., RIP processing by the plate making RIP processor 54A)
including halftone dot processing. Moreover, as the density in the
boundary portion (edge portion) between the image portion (high density
portion) and the background portion (low density portion) in the image
(original image) represented by the printing data becomes lower, the area
ratio of the halftone dots in the image portion in the image represented
by the plate making binary data drops, and the distance between the dots
configuring the halftone dots becomes larger. Due thereto, a phenomenon
arises where the change in the density (density change) in the edge
portion in the image represented by the plate making binary data becomes
duller than in the original image. If the original image is an image
representing a text document, since the density in the edge portion is
relatively high, the above-described phenomenon is difficult to see.
However, when the original image is a photo image or an image in which a
photo image and an image representing a text document are mixed, often
the density in the edge portion within the photo image is lower than that
of the image representing the text document. For that reason, the
dullness of the density change in the edge portion in the image
represented by the plate making binary data may be seen relatively
remarkably.

[0088]Therefore, when creating a printing plate of a photo image or an
image in which a photo image and an image representing a text document
are mixed by the plate making apparatus 24 and performing printing by the
printing machine 22, often edge enhancement processing is performed
beforehand with respect to the printing data by the terminal device 36,
for example, in anticipation of the density change in the edge portion
within the photo image of the plate making binary data becoming dull in
accompaniment with the RIP processing. Thus, as indicated by the solid
line in FIG. 10 for example, the dullness of the density change in the
edge portion within the photo image of the plate making binary data after
RIP processing is alleviated by the edge enhancement processing performed
beforehand with respect to the printing data (note that although the
solid line in FIG. 10 shows the density change in the edge portion within
the photo image of the descreened data, the edge portion within the photo
image of the binary data before descreening also shows the same change).

[0089]However, in RIP processing (e.g., RIP processing by the printer RIP
processor 54B) that generates printer multi-value data from printing
data, dullness of the density change in the edge portion within the photo
image such as described above does not arise. Therefore, as indicated by
the broken line in FIG. 10 for example, in the edge portion within the
photo image of the printer multi-value data, the density changes
precipitously because of the edge enhancement processing that has been
performed with respect to the printing data. As is apparent by comparing
the solid line with the broken line shown in FIG. 10, the density change
in the edge portion within the photo image differs greatly between the
descreened data and the printer multi-value data.

[0090]In the moire determination processing previously described in the
first and second exemplary embodiments, based on the fact that the
density in the background portion in an image representing a text
document is 0 or close to 0, 0 is set to the value Oni of color i of the
pixel in pixel position n in the determination image when the value Cn1i
of color i of the pixel in pixel position n of the printer multi-value
data is 0 (i.e., when the determination of step S168 is positive). Thus,
as shown also in FIG. 5B, the edge component corresponding to a change in
density in the background portion side of the edge portion (i.e., a
change in density such that the value Dn1i of the descreened data is
higher than the value Cn1i of the printer multi-value data or the sum of
the determination reference value Cm and the determination threshold
value Th0) is removed from the determination image. However, in a photo
image, the background portion also has density to a certain extent.
Therefore, even when the above-described processing is applied to a photo
image or an image in which a photo image and an images representing a
text document are mixed, as shown in FIG. 10, the edge component
corresponding to the density change in the background portion side of the
edge portion within the photo image is not removed from the determination
image. Further, when a value larger than 0 is used as the determination
threshold value (second value) to be compared with the value Cn1i of the
printer multi-value data, the precision of removing the edge component
within the image representing the text document from the determination
image drops.

[0091]In consideration of the above, in the third exemplary embodiment,
the moire determination processing shown in FIG. 9 is performed. Below,
only those portions of the moire determination processing pertaining to
the third exemplary embodiment that differ from the moire determination
processing of the second exemplary embodiment (FIGS. 7A and 7B) will be
described. In the moire determination processing of the third exemplary
embodiment, the program performs smoothing processing in step 160 with
respect to the printer multi-value data and the descreened data subjected
to pixel number adjustment processing. Thereafter, in the next step 210,
edge enhancement processing is performed with respect to the printer
multi-value data that have undergone pixel number adjustment processing
and also with respect to the descreened data that have undergone
smoothing processing. The descreened data that have undergone the edge
enhancement processing of step 210 will hereinafter be called
"edge-enhanced descreened data" (fifth image data).

[0092]The edge enhancement processing with respect to the descreened data
of step 210 can be realized in the same way as in step 161 described in
the second exemplary embodiment (FIGS. 7A and 7B). That is, the edge
enhancement processing can be realized by processing such as using an
edge extraction filter such as a differential filter, for example, to
extract the edge component from the descreened data that have undergone
smoothing processing, multiplying the extracted edge component with a
preset coefficient, and adding the product to the original descreened
data. Thus, from the descreened data, as indicated by the bold solid line
in FIG. 11 for example, image data (edge-enhanced descreened data) that
show a change in value in the edge portion within the photo image similar
to that of the printer multi-value data and in which the moire component
superimposed on the descreened data is preserved. The edge enhancement
processing with respect to the descreened data of step 210 is a
processing corresponding to the function of the edge enhancement
processor 130 (see FIG. 8).

[0093]In the next step 212, the variable n is initialized to 0. In step
214, a value representing any of C, M, Y, K is set to the variable i. In
step 216, a determination is made are to whether or not there is a pixel
in pixel position n. When the determination of step 216 is positive, the
processing moves to step 218; where a determination is made as to whether
or not the value Cn1i of color i of the pixel in pixel position n of the
printer multi-value data is equal to or less than a preset determination
threshold value Th3 (second value). As the determination threshold value
Th3, 0 or a value close to 0 (e.g., a value of about 2 to 6% in terms of
the percentage of the density value) can be set.

[0094]When the determination of step 218 is negative, the processing moves
to step 220, where the maximum value of the value Cn1i of color i of the
pixel in pixel position n of the printer multi-value data, the value Cn2i
of color i of the pixel in pixel position n of the smoothed printer
multi-value data and the value Cn3i of color i of the pixel in pixel
position n of the edge-enhanced printer multi-value data is set for a
determination reference value Cm (seventh image data). Further, in the
next step 222, the minimum value of the value Dn1i of color i of the
pixel in pixel position n of the descreened data and a value Dn2i of
color i of the pixel in pixel position n of the edge-enhanced descreened
data is set for a determination reference value Dm (sixth image data).

[0095]In the next step 224, a determination is made as to whether or not
the sum of the determination reference value Cm and the determination
threshold value Th0 is smaller than the determination reference value Dm.
When this determination is positive, the processing moves to step 226,
where a determination is made as to whether or not the value Cn2i is
equal to or greater than the sum of the value Cn1i and a preset
determination threshold value Th4 (sixth value), and whether or not the
value Cn3i is smaller than a preset determination threshold value Th5
(seventh value).

[0096]When the determination of step 218 is positive or when the
determination of step 224 is negative or when the determination of step
226 is positive, the processing moves to step 228, sets 0 as the value
Oni of color i of the pixel in pixel position n in the determination
image, and then moves to step 232. the value (=0) set for the value Oni
in step 228 is an example of the third value. When the determination of
step 218 is negative and the determination of step 224 is positive and
the determination of step 226 is negative, the processing moves to step
230, where the difference between the determination reference value Dm
and the determination reference value Cm is set to the value Oni
(corresponding to "a value differing from the third value" or "a value
corresponding to the difference between the value of the sixth image data
and the value of the seventh image data"). Thereafter, the processing
moves to step 232.

[0097]In step 232, a determination is made as to whether or not the
processing of step 218 to step 230 has been performed with respect to all
of the colors of C, M, Y, K of the pixel in pixel position n. When the
determination is negative, a value representing the unprocessed color of
C, M, Y, K is set for the variable i in step 234 and then the processing
returns to step 218. Thus, the processing of step 218 to step 234 is
performed with respect to all of the colors of C, M, Y, K of the pixel in
pixel position n. Further, when the determination of step 232 is
positive, the variable n is updated (e.g., incremented by 1) and
thereafter the processing returns to step 214. Thus, the processing of
step 218 to step 234 is performed per each color of C, M, Y, K with
respect to all pixels in the image represented by the descreened data and
in the image represented by the printer multi-value data. Step 212 to
step 236 in the moire determination processing of the third exemplary
embodiment are processing corresponding to the function of the
determination image generator 118 (see FIG. 8).

[0098]The processing of step 218 to step 234 will be described further
with reference to FIG. 11 and FIG. 12. In the processing of step 218 to
step 234, the maximum value of the value Cn1i, the value Cn2i and the
value Cn3i is set to the reference value Cm (step 220), and the minimum
value of the value Dn1i and the value Dn2i is set to the reference value
Dm (step 222). The determination is made as to whether or not the sum of
the reference value Cm and the threshold value Th0 is smaller than the
reference value Dm (step 224) and, when this determination is negative,
the value Oni is set to 0 (step 228).

[0099]Here, the value Dn2i of the edge-enhanced descreened data is, as
indicated by the bold solid line in FIG. 11 for example, image data that
show a change in value in the edge portion within the photo image similar
to that of the printer multi-value data and in which the moire component
superimposed on the descreened data is preserved. For that reason, the
determination reference value Dm that is the minimum value of the value
Dn2i and the value Dn1i becomes, as indicated by the solid line in FIG.
12, data that show a change in value in the background portion side of
the edge portion within the photo image similar to that of the printer
multi-value data. However, a change in value in the image portion side of
the edge portion within the photo image shows transition in lower value
than that of the printer multi-value data, and the moire component is
preserved in the image portion side. Consequently, by setting the value
Oni to 0 when the reference value Dm is equal to or less than the sum of
the reference value Cm and the threshold value Th0, as is apparent by
FIG. 12 compared with FIG. 10, the edge component extracted as the
determination image is reduced while the moire component extraction
performance is maintained.

[0100]Further, in the processing of step 218 to step 234, the
determination is made as to whether or not the value Cn2i is equal to or
greater than the sum of the value Cn1i and the threshold value Th4 and
whether or not the value Cn3i is smaller than the threshold value Th5
(step 226) and, when this determination is also positive, the value Oni
is set to 0 (step 228). The determination in step 226 of whether or not
the value Cn3i is smaller than the threshold value Th5 is a determination
for removing, from the target, a case where the value Cn3i is clearly
outside the range of values corresponding to a change in density in the
background portion side in the edge portion within a photo image. As the
threshold value Th5, a value of about 30 to 40% in terms of the
percentage of the density may be set (one example is shown in FIG. 13).

[0101]On the other hand, as for the value Cn2i of the smoothed printer
multi-value data, as indicated by the bold solid line in FIG. 13 for
example, the density change in the edge portion within the photo image
becomes dull because of smoothing, and in the background portion side of
the edge portion within the photo image, the value Cn2i changes at a
value equal to or greater than the sum of the value Cn1i and the
threshold value Th4. Consequently, the value Oni is set to 0 when the
value Cn2i is equal to or greater than the sum of the value Cn1i and the
threshold value Th4 and the value Cn3i is smaller than the threshold
value Th5. Thus, as shown in FIG. 13, a situation where the edge
component corresponding to the density change in the background portion
side of the edge portion within the photo image is extracted as the
determination image is reduced.

[0102]Moreover, in the processing of step 218 to step 234, the
determination is made as to whether or not the value Cn1i is equal to or
less than the threshold value Th3 (step 218) and, when this determination
is positive, the value Oni is also set to 0 (step 228). Thus, even if the
original image of the printing target is an image in which images of a
photo image and a text document are mixed, for the edge portion of the
image of the text document, the edge portion corresponding to the density
change in the background portion side of the edge portion is removed from
the determination image as a result of the determination of step 218
being positive.

[0103]Consequently, a value corresponding to the amplitude of the moire
component is set only to pixels (moire pixels) corresponding to moire
occurring in the plate making binary data and remaining in the descreened
data per each color of C, M, Y, K due to the processing of step 218 to
step 234. For pixels other than the moire pixels, the determination image
is obtained in which the value thereof is set to 0 regardless of whether
they are pixels corresponding to a photo image or pixels corresponding to
a text document, and even if they are pixels corresponding to the edge
portion within a photo image.

[0104]When the determination image is generated as a result of the
processing of step 218 to step 234 for each color of C, M, Y, K of all
pixels in the image represented by the descreened data and in the image
represented by the printer multi-value data, the determination of step
216 is negative and the processing moves to step 238, where noise removal
processing is performed with respect to the generated determination
image. For this noise removal processing, known noise removal techniques
can be applied, such as a smoothing filter, a Gaussian filter, fast
Fourier transform (FFT), contraction by morphology, and isolated point
removal. The noise removal processing of step 238 is processing
corresponding to the function of the noise remover 130 (see FIG. 8). In
the next step 240, determination image generation and output processing
is performed, but these are the same processings as in step 182 to step
200 shown in FIGS. 4Am 4B, FIGS. 7A and 7B, and therefore description
thereof will be omitted.

[0105]In the third exemplary embodiment, the edge enhancement processing
is performed with respect to the descreened data in steps 220 to 224 and
step 228. As a result, from the descreened data, edge-enhanced descreened
data that show a change in value in the edge portion within a photo image
similar to that of the printer multi-value data and in which the moire
component superimposed on the descreened data is preserved. The value Oni
of the determination image is set to 0 when the reference value Dm that
is the minimum value of the value Dn1i and the value Dn2i is equal to or
less than the printer multi-value data (specifically, the sum of the
threshold value Th0 and the reference value Cm determined from the value
Cn1i). Thus, a situation is reduced where the edge component
corresponding to the density change in the background portion side of the
edge portion within a photo image is extracted as the determination
image. Alternately, the following processing may be performed instead of
this processing.

[0106]That is, making the change in the value in the edge portion within a
photo image similar between the printer multi-value data and the
descreened data can also be realized by performing smoothing processing
on the printer multi-value data instead of performing edge enhancement
processing with respect to the descreened data as described above. By
adjusting the order (the size of the region to be the processing unit) of
the filter used in the smoothing processing with respect to the printer
multi-value data and the strength of the smoothing, as shown in FIG. 14
for example, the change in the value in the edge portion within the photo
image of the smoothed printer data (indicated by the bold solid line in
FIG. 14) can be made to approximate the change in the value in the edge
portion within the photo image of the descreened data (indicated by the
fine solid line in FIG. 14).

[0107]Consequently, instead of the processing of steps 220 to 224 and step
228 previously described, a processing may be performed in which the
value of the descreened data is compared with the sum of the smoothed
printer data and the determination threshold value Th0 and the value Oni
is set to 0 when the value of the descreened data is equal to or less
than the sum of the smoothed printer data and the threshold value Th0. In
this case also, as shown in FIG. 15 for example, a situation where the
edge component corresponding to the density change in the background
portion side of the edge portion within the photo image is extracted as
the determination image is reduced.

[0108]However, in this aspect, when the strength of smoothing with respect
to the printer data is insufficient or the like, the effect of
suppressing a situation where the edge component of the edge portion
within the photo image is extracted as the determination image may drop.
Further, when the strength of smoothing with respect to the printer data
is excessive, for a portion where the density finely changes in the
original image, that change is made uniform and the value becomes smaller
in the smoothed printer data, whereby the value in the descreened data of
that portion becomes larger than that in the smoothed printer data and
the pixels corresponding to that portion may be erroneously extracted as
moire pixels. For this reason, in this aspect, the order and strength of
the smoothing processing with respect to the printer data may be needed
to be finely adjusted such that the dulling of the change in value
resulting from the smoothing processing with respect to the printer data
being about the same as the dulling of the change in density in the plate
making binary data due to the RIP processing.

Fourth Exemplary Embodiment

[0109]Next, a fourth exemplary embodiment will be described. The same
reference numerals will be given to portions that are the same as those
in the second exemplary embodiment, and description of those portions
will be omitted. As shown in FIG. 16, the moire determination unit 110
pertaining to the fourth exemplary embodiment differs from the moire
determination unit 110 of the third exemplary embodiment in that a
neighboring N pixel maximum value extractor 134 is added. Further, with
respect to the determination image generator 118, a maximum value of
neighboring N pixels of the printer multi-value data outputted from the
neighboring N pixel maximum value extractor 134 is also inputted thereto
in addition to the printer multi-value data outputted from the pixel
number adjuster 114A, the smoothed printer multi-value data outputted
from the smoothing processor 116A, the edge-enhanced printer multi-value
data outputted from the edge enhancement processor 128, the descreened
data outputted from the smoothing processor 116B, and the edge-enhanced
descreened data outputted from the edge enhancement processor 130A.

[0110]The moire determination processing pertaining to the fourth
exemplary embodiment will be described with reference to FIG. 17. In the
moire determination processing described in the third exemplary
embodiment (FIG. 9), in step 220, the maximum value of the value Cn1i of
the printer multi-value data, the value Cn2i of the smoothed printer
multi-value data and the value Cn3i of the edge-enhanced printer
multi-value data is set for the determination reference value Cm. The
moire determination processing pertaining to the fourth exemplary
embodiment differs from the moire determination processing of the third
exemplary embodiment only in that, instead of the above-described
processing, in step 221, the maximum value of the value Cn2i of color i
of the pixel in pixel position n of the smoothed printer multi-value
data, the value Cn3i of color i of the pixel in pixel position n of the
edge-enhanced printer multi-value data and a maximum value Cn4i of color
i of N (N≧2) number of pixels existing in the neighborhood of the
pixel in pixel position n of the printer multi-value data is set for the
determination reference value Cm.

[0111]The maximum value Cn4i of color i of the N number of pixels
neighboring the pixel in pixel position n of the printer multi-value data
corresponds to eighth image data, and the reference value Cm set in step
221 corresponds to seventh image data. Further, in step 221, the
processing that extracts the maximum value Cn4i per each of the
individual pixels of the value Cn1i is processing corresponding to the
function of the neighboring N pixel maximum value extractor 134 (see FIG.
17).

[0112]In the moire determination processing pertaining to the fourth
exemplary embodiment, processing from the next step 222 on is the same as
in the moire determination processing described in the third exemplary
embodiment. The minimum value of the value Dn1i and the value Dn2i is set
for the reference value Dm (step 222), a determination is made as to
whether or not the sum of the reference value Cm and the threshold value
Th0 is smaller than the reference value Dm (step 224), and the value Oni
is set to 0 when this determination is negative (step 228).

[0113]The processing of step 221 to step 224 and step 228 will be
described further with reference to FIG. 18 to FIG. 22. As mentioned
above, in step 221, the maximum value of the value Cn2i, the value Cn3i
and the maximum value Cn4i is set for the reference value Cm. The maximum
value Cn4i is image data obtained by extracting and setting the maximum
value of color i of the N number of pixels existing in the neighborhood
per each of the individual pixels of the printer multi-value data.
Therefore, as indicated by the one-dotted chain line in FIG. 18 for
example, in the edge portion within the photo image, the position where
the values change moves N pixels toward the background portion side with
respect to the values of the printer multi-value data and the value
changes in higher values than that of the reference value Dm (the minimum
value of the value Dn1i and the value Dn2i) across substantially the
entire edge portion within the photo image.

[0114]The reference value Cm is the maximum value of the value Cn2i, the
value Cn3i and the maximum value Cn4i. Consequently, in the edge portion
within the photo image, the maximum value Cn4i of the neighboring N
pixels where the position where the values change has moved N pixels
toward the background portion side with respect to that of the printer
multi-value data becomes the reference value Cm. Consequently, the sum
(indicated by the broken line in FIG. 19) of this reference value Cm
(=the maximum value Cn4i) and the threshold value Th0 is compared with
the reference value Dm, and the value Oni is set to 0 when the sum of the
reference value Cm and the threshold value Th0 is equal to or greater
than the reference value Dm. Thus, as shown in FIG. 19, a situation where
the edge component corresponding to the density change of the edge
portion within the photo image is extracted as the determination image is
prevented or reduced.

[0115]There is the potential for screen noise that has not be removed even
by the smoothing processing described in the first exemplary embodiment
to be superimposed on the descreened data (one example is indicated by
the solid line in FIG. 20). Also on the printer image data, if the
original image is a photo image, noise (noise whose cycle is shorter than
that of screen noise; one example is indicated by the bold broken line in
FIG. 20) caused by an imaging element such as a CCD of a digital camera
may be superimposed in high potential.

[0116]When screen noise had been superimposed on the descreened data and
noise had been superimposed also on the printer data, for example, even
if the moire determination processing described in the first to third
exemplary embodiments have been applied, for example, as shown in FIG.
20, in a portion in the image where the density is substantially uniform,
a portion where the value Dn1i (or the reference value Dm) becomes higher
than the sum of the value Cn1i (or the reference value Cm) and the
threshold value Th0 arises because of fluctuation in the value of each
set of data caused by the noise superimposed thereon, and the pixels of
this portion can be erroneously extracted as moire pixels.

[0117]With respect thereto, in the moire determination processing
pertaining to the fourth exemplary embodiment, if the distribution length
on the image of the N number of pixels used in the calculation of the
maximum value Cn4i is equal to or greater than the length on the image of
the cycle of noise superimposed on the printer data, in a portion in the
image where the density is substantially uniform, as indicated by the
one-dotted chain line in FIG. 21, the maximum value Cn4i will be a
constant value corresponding to the maximum value of the printer
multi-value data in that portion. For this reason, in a portion in the
image where the density is substantially uniform, the maximum value Cn4i
is the reference value Cm. Thus, as shown in FIG. 22, the portion where
the reference value Dm (indicated by the solid line in FIG. 22) is higher
than the sum (indicated by the fine broken line in FIG. 22) of the
reference value Cm and the threshold value Th0 disappears, whereby a
situation where the moire pixels are erroneously extracted because of the
affect of noise superimposed on the descreened data and the printer data
is prevented or reduced.

[0118]When the distribution length on the image of the N number of pixels
is shorter than the length on the image of the cycle of the noise
superimposed on the printer data, although fluctuations in value arise,
the maximum value Cn4i will be the maximum value of the printer
multi-value data or a value close to that maximum value. For that reason,
the portion where the reference value Dm is higher than the sum of the
reference value Cm and the threshold value Th0 is reduced, and the moire
pixels erroneously extracted due to the affect of noise superimposed on
the descreened data and the printer data are reduced.

Fifth Exemplary Embodiment

[0119]Next, a fifth exemplary embodiment will be described. The same
reference numerals will be given to portions that are the same as those
in the third exemplary embodiment, and description of those same portions
will be omitted. As shown in FIG. 23, the moire determination unit 110
pertaining to the fifth exemplary embodiment differs from the moire
determination unit 110 of the third exemplary embodiment in that a
neighboring N pixel minimum value extractor 136 to which the
edge-enhanced descreened data outputted from the edge enhancement
processor 130A are inputted is added. Further, with respect to the
determination image generator 118, a minimum value of neighboring N
pixels of the edge-enhanced descreened data outputted from the
neighboring N pixel minimum value extractor 136 is also inputted thereto
in addition to the printer multi-value data outputted from the pixel
number adjuster 114A, the smoothed printer multi-value data outputted
from the smoothing processor 116A, the edge-enhanced printer multi-value
data outputted from the edge enhancement processor 128, and the
descreened data outputted from the smoothing processor 116B.

[0120]The moire determination processing pertaining to the fifth exemplary
embodiment will be described with reference to FIG. 24. In the moire
determination processing of the third exemplary embodiment (FIG. 9), in
step 220, the maximum value of the value Cn1i, the value Cn2i and the
value Cn3i is set for the determination reference value Cm and thereafter
in step 222, the minimum value of the value Dn1i and the value Dn2i is
set for the determination reference value Dm. The moire determination
processing pertaining to the fifth exemplary embodiment differs from the
moire determination processing described in the third exemplary
embodiment only in that, instead of the processing of step 222, in step
223, the minimum value of the value Dn1i of the descreened data and a
minimum value Dn3i of color i of N (N≧2) number of pixels existing
in the neighborhood of the pixel in pixel position n of the edge-enhanced
descreened data is set for the determination reference value Dm.

[0121]The minimum value Dn3i of color i of the N number of pixels
neighboring the pixel in pixel position n of the edge-enhanced descreened
data corresponds to ninth image data, and the determination reference
value Dm set in step 223 corresponds to tenth image data. Further, in
step 223, the processing that extracts the minimum value Dn3i is
processing corresponding to the function of the neighboring N pixel
minimum value extractor 136 (see FIG. 23).

[0122]In the moire determination pertaining to the fifth exemplary
embodiment, processing from the next step 224 on is the same as that in
the moire determination processing described in the third exemplary
embodiment. The determination is made as to whether or not the sum of the
reference value Cm and the threshold value Th0 is smaller than the
reference value Dm (step 224), and the value Oni is set to 0 when this
determination is negative (step 228).

[0123]The processing of steps 220, 223, 224 and 228 will be described
further with reference to FIG. 25 to FIG. 28. As mentioned above, in step
223, the minimum value of the value Dn1i and the minimum value Dn3i is
set for the reference value Dm. The minimum value Dn3i is image data
obtained by extracting and setting the minimum value of color i of the N
number of pixels existing in the neighborhood per each of the individual
pixels of the edge-enhanced descreened data. Therefore, as indicated by
the one-dotted chain line in FIG. 25 for example, in the edge portion
within the photo image, the position where the values change moves N
pixels toward the image portion side with respect to that of the
edge-enhanced descreened data, and the values changes in lower values
than that of the reference value Cm (the maximum value of the value Cn1i,
the value Cn2i and the value Cn3i) across substantially the entire edge
portion within the photo image.

[0124]The reference value Dm is the minimum value of the value Dn1i and
the minimum value Dn3i. Therefore, in the edge portion within the photo
image, the minimum value Dn3i of the neighboring N pixels where the
position where the values change has moved N pixels toward the image
portion side with respect to that of the edge-enhanced descreened data
becomes the reference value Dm. Consequently, this reference value Dm
(=the minimum value Dn3i indicated by the solid line in FIG. 26) is
compared with the sum (indicated by the broken line in FIG. 26) of the
reference value Cm and the threshold value Th0, and the value Oni is set
to 0 when the reference value Dm is equal to or less than the sum of the
reference value Cm and the threshold value Th0. Thus, as shown in FIG.
26, a situation where the edge component corresponding to the density
change of the edge portion within the photo image is extracted as the
determination image is prevented or reduced.

[0125]Further, when screen noise had been superimposed on the descreened
data and noise had been superimposed also on the printer data, in the
moire determination processing of the fifth exemplary embodiment, in a
portion in the image where the density is substantially uniform, the
minimum value Dn3i (indicated by the one-dotted chain line in FIG. 27)
exhibits a change where the period in which it exhibits a relatively high
value with respect to the change in the value Dn1i (indicated by the
solid line in FIG. 27) becomes shorter and the period in which it
exhibits a relatively low value becomes longer. The minimum value Dn3i in
a portion in the image where the density is substantially uniform is not
constant as the maximum value Cn4i of the neighboring N pixels of the
printer multi-value data in the fourth exemplary embodiment. This is
because it is necessary to make the value of N larger in order to make
the minimum value Dn3i constant since the cycle of the screen noise
superimposed on the descreened data is longer than that of the noise
superimposed on the printer data, and when the value of N is made too
large, this has an adverse impact on the moire pixel extraction
performance.

[0126]Due to the minimum value Dn3i changes in a portion in the image
where the density is substantially uniform as described above, the
minimum value Dn3i becomes the reference value Dm in the portion in the
image where the density is substantially uniform. As shown in FIG. 28,
due to the portion where the reference value Dm (indicated by the solid
line in FIG. 28) is higher than the sum (indicated by the fine broken
line in FIG. 22) of the reference value Cm and the threshold value Th0
decreases, a situation where the moire pixels are erroneously extracted
due to the affect of noise superimposed on the descreened data and the
printer data is reduced.

[0127]In the above description, an aspect has been described in which the
number of pixels (moire pixels) where at least one value of each color of
C, M, Y, K of each pixel in the determination image is equal to or
greater than the determination threshold value Th1 is counted(step 182),
a determination is made as to whether or not there is moire on the basis
of whether or not the result of counting the moire pixels (the number of
moire pixels) is equal to or greater than the determination threshold
value Th2, and the determination result is displayed on the display 40 of
the terminal device 36 (step 184). However, exemplary embodiments are not
limited to this and may also be configured such that the result of
counting the moire pixels or the percentage of moire pixels occupying the
total number of pixels are presented to the user, and the user may
determine whether or not there is moire.

[0128]In the moire determination processing described in the first
exemplary embodiment (FIGS. 4A and 4B), the difference between the value
Dn1i and both the value Cn1i and the determination threshold value Th0 is
set as the value Oni of the determination image (step 174) when the value
Cn1i of the printer multi-value data is not 0 (when the determination of
step 168 is negative) and the sum of the value Cn1i and the determination
threshold value Th0 is smaller than the value Dn1i of the descreened data
(when the determination of step 170 is positive). However, exemplary
embodiments are not limited to this and may also be configured such that
the determination threshold value Th0 is not used and the difference
between the value Dn1i and the value Cn1i may be set as the value Oni of
the determination image when the value Cn1i is not 0 and the value Cn1i
is smaller than the value Dn1i of the descreened data. In regard to the
moire determination processing described in the second exemplary
embodiment (FIGS. 7A and 7B), the difference between the value Dn1i and
both the value Cn2i of the smoothed printer multi-value data and the
determination threshold value Th0 is set as the value Oni of the
determination image (step 175) when the value Cn1i of the printer
multi-value data is not 0 (when the determination of step 168 is
negative) and the sum of the determination reference value Cm and the
determination threshold value Th0 is smaller than the value Dni of the
descreened data (when the determination of step 171 is positive).
However, exemplary embodiments are not limited to this and may also be
configured such that the determination threshold value Th0 is not used
and difference between the value Dn1i and the value Cn2i may be set as
the value Oni of the determination image when the value Cn1i is not 0 and
the determination reference value Cm is smaller than the value Dn1i of
the descreened data. The same modification may be applied to the third to
fifth exemplary embodiments. Although it becomes easier than in the
aspect where the determination threshold value Th0 is used to be affected
by noise remaining in the printer multi-value data and the descreened
data when the determination threshold value Th0 is not used as described
above, such an aspect is also included in the scope of disclosure.

[0129]In the first and second exemplary embodiments, aspects are described
in which the second value is set to "0", and in the first to fifth
exemplary embodiments, aspects are described in which the third value is
set to "0". However, exemplary embodiments are not limited to this, and
the second value may also be a value that is larger than 0 but close to
0. Further, it suffices for the third value to be a value with which
moire pixels whose values corresponding to the moire component are to be
set can be clearly distinguished in an image from non-moire pixels that
are to be set the third value. For example, a tag representing whether or
not a pixel is a non-moire pixel may be provided per each pixel and per
each color, the value of a non-moire pixel may be tentatively set to 0,
information indicating that a pixel is a non-moire pixel may be set in
the tag, and at the time of output of the determination image of any
color of the colors of C, M, Y, K, the value (third value) of the
non-moire pixels may be reset such that the non-moire pixels are
outputted in a different color than that of the moire pixels.

[0130]Moreover, in the moire determination processing (FIG. 9) pertaining
to the third exemplary embodiment and the moire determination processing
(FIG. 24) pertaining to the fifth exemplary embodiment, in step 224, the
determination reference value Dm is compared with the sum of the
determination reference value Cm and the determination threshold value
Th0. However, the exemplary embodiments are not limited to this. The
processing may also be configured to use the printer multi-value data
(second image data) instead of the determination reference value Cm and
compare the determination reference value Dm with the sum of the value
Cn1i of the printer multi-value data and the determination threshold
value Th0. Although the precision of the removal of the edge component
from the determination image drops when the value Cn1i of the printer
multi-value data is used instead of the determination reference value Cm,
such an aspect can also be included in the scope of disclosure.

[0131]Further, in the moire determination processing pertaining to the
fourth exemplary embodiment (FIG. 17), in step 224, the determination
reference value Dm is compared with the sum of the determination
reference value Cm and the determination threshold value Th0. However,
exemplary embodiments are not limited to this. The processing may also be
configured to use the descreened data (first image data) instead of the
determination reference value Dm, and compare the value Dn1i of the
descreened data with the sum of the determination reference value Cm and
the determination threshold value Th0. Although the precision of the
removal of the edge component from the determination image drops when the
value Dn1i of the descreened data is used instead of the determination
reference value Dm, such an aspect can also be included in the scope of
rights of the present application.

[0132]Further, in the moire determination processing pertaining to the
third exemplary embodiment (FIG. 9), the moire determination processing
pertaining to the fourth exemplary embodiment (FIG. 17) and the moire
determination processing pertaining to the fifth exemplary embodiment
(FIG. 24), in step 218, a determination is made as to whether or not the
value Cn1i of the printer multi-value data was equal to or less than the
determination threshold value Th3 and, when the determination is
positive, the value Oni of the determination image is set to 0 in step
228. However, exemplary embodiments are not limited to this. For example,
it is also possible to omit the above-described determination when, for
example, an image portion corresponding to a text document is not
included in the original image.

[0133]Moreover, in the moire determination processing pertaining to the
third exemplary embodiment (FIG. 9), the moire determination processing
pertaining to the fourth exemplary embodiment (FIG. 17) and the moire
determination processing pertaining to the fifth exemplary embodiment
(FIG. 24), in step 226, a determination is made as to whether or not the
value Cn2i of the smoothed printer multi-value data is equal to or
greater than the sum of the value Cn1i of the printer multi-value data
and the determination threshold value Th4 and whether or not the value
Cn3i of the edge-enhanced printer multi-value data is smaller than the
determination threshold value Th5 and, when the determination is
positive, the value Oni of the determination image is set to 0 in step
228. This processing may also be added to the moire determination
processing pertaining to the first exemplary embodiment (FIGS. 4A and 4B)
and the moire determination processing pertaining to the second exemplary
embodiment (FIGS. 7A and 7B).

[0134]In the above description, embodiments are described in which the
original image is outputted (display on a display device, printing on
recording paper, etc.) together with the determination image. However,
exemplary embodiments are not limited to this. In the above-described
exemplary embodiments, the edge component is removed from the
determination image. Therefore, although a moire component had been
clearly manifest on the determination image, it may be difficult for a
user to judge, just by referencing the determination image, whether the
region on the determination image in which the moire component is clearly
manifest corresponds to what region in the original image. Outputting the
original image together with the determination image has the purpose of
aiding this judgment. However, the edge component may also be extracted
from the original image (e.g., the printer multi-value data that have
undergone pixel number adjustment processing) and the extracted edge
component may be added to the determination image. Further, when
displaying the determination image on a display device, enhancement of
the edge component to be added to the determination image may be changed
in real time in response to an instruction from the user. Thus, it
becomes possible to judge, just by referencing the determination image,
whether what region the region on the determination image in which the
moire component is clearly manifest corresponds to in the original image,
and it is possible to omit the outputting of the original image together
with the determination image. The aspect described above is also included
in the scope of disclosure.

[0135]In the above description, embodiments are described in which the
resolution of the data of the determination image matches the resolution
of the print image data usable in printing by the image formation
apparatus 12, whereby it is unnecessary to convert the resolution of the
data of the determination image at the time of printing of the
determination image by the image formation apparatus 12. However,
exemplary embodiments are not limited to this, and the resolution of the
data of the determination image may not be matched with the resolution of
the print image data usable in printing by the image formation apparatus
12. For example, when the resolution of the print image data usable in
printing by the image formation apparatus 12 is 600 dpi, the resolution
of the data of the determination image may be made 1200 dpi, and when the
determination image is to be printed by the image formation apparatus 12,
the resolution of the data of the determination image may be converted
from 1200 dpi to 600 dpi.

[0136]In the above description, embodiments are described in which, after
the determination image has been generated, the generated determination
image is displayed on the display of the terminal device 36 and the
determination image is printed on recording paper by the image formation
apparatus 12 when the printing is instructed to the terminal device 36.
However, exemplary embodiments are not limited to this and may also be
configured to perform printing of the determination image on a recording
paper each time the moire determination is instructed or may also be
configured such that one of display of the determination image on a
display device or printing of the determination image on a recording
paper is omitted.

[0137]The printing apparatus that prints the determination image is not
limited to a configuration where printing of an image is performed by an
electrophotographic system like the image formation apparatus 12 and may
also have a configuration where printing of an image is performed by
other publicly known system such as an inkjet system.

[0138]In the above description, embodiments are described in which the
printing server 26 is configured to function as the image processing
apparatus. However, exemplary embodiments are not limited to this. The
image formation apparatus 12 may be configured to function as the image
processing apparatus, or the terminal device 36 may be configured to
function as the image processing apparatus pertaining.

[0139]In the above description, embodiments are described in which the
moire determination program corresponding to the image processing program
is stored (installed) beforehand in the storage unit 28C of the printing
server 26. However, the image processing program may be provided in a
form of being recorded in a recording medium such as a CD-ROM or a
DVD-ROM.